Research On Modeling And Simulation Of Propulsion System Of Pure Battery Ship

With the deepening of the carbon peaking and carbon neutrality goals,in the field of ships,new energy inland ships,such as battery ships and hydrogen-powered ships,have become hot spots for research.Compared with diesel-powered ships,these new energy ships have significant advantages of no pollution and low noise.Among them,pure battery boats have the characteristics of high energy density and long endurance.The anti-interference ability and stability of the ship’s electric propulsion system are related to the power output characteristics of the electric propulsion system,and are the key aspects that need to be considered in the development process of electric propulsion ships.However,the power density of lithium iron phosphate batteries is limited,the dynamic response speed is slow,and the sudden change in the power load of the ship will lead to the imbalance between battery power supply and electricity demand,which will cause the bus voltage and current to fluctuate sharply,and reduce the stability of the DC power grid.At the same time,the continuous fluctuation of power load will reduce the service life of lithium iron phosphate batteries.In view of the above problems,this paper adopts the combination of lithium iron phosphate battery and super capacitor to form a composite energy storage system,and uses the characteristics of high power density and fast response of super capacitor to compensate for the shortcomings of low power density of lithium iron phosphate battery,smooth the power output fluctuation of the battery,stabilize the DC link voltage,and improve the reliability and safety of the electric propulsion system.At the same time,this paper builds a model of electric propulsion system combining pure battery ship and super capacitor,and conducts simulation tests on sudden load,and verifies the stability of the electric propulsion system of the ship.The main work is as follows:This paper is based on the first pure battery ship "Navigator Star" in Heilongjiang Province.Firstly,the composite energy storage system of the ship is modeled,including the introduction of the target ship and the energy storage system,the selection and parameter matching of the energy storage system,and the characteristics analysis and model construction of the power battery,super capacitor and bidirectional DC/DC converter are carried out.Secondly,based on the voltage stabilization control method of DC power grid,the control strategy of composite energy storage system is simulated and integrated by filtering algorithm and improved drooping power distribution mode,and the effectiveness of the control strategy is verified,which effectively reduces the large power fluctuation of the battery and makes the high-frequency power fluctuation borne by the supercapacitor.Then,based on simulate software,the propulsion motor was selected,the control system of the propulsion motor was modeled and simulated,the control strategy of the propulsion motor was formulated,and the vector control model of the motor was built,and the load burst experiment of the motor model could prove the correctness and effectiveness of the motor parameter setting and control system.Finally,the oar system is modeled and simulated,and a series of simulation studies are carried out on the propeller starting mode,which verifies the correctness of the overall model of the propeller.The modules of the ship’s electric propulsion system are integrated,and the overall simulation and analysis are carried out,and the simulation test is carried out under the condition of load change,and the results show that the model established in this paper can cope with load change,and the supercapacitor and the control strategy formulated in this paper can play a role in protecting the battery and enhancing the stability of the electric propulsion system.